Toxicity of currently used ionic radiographic contrast media (CM) is a result of their hydrophobicity, charge, and solution hypertonicity. Nonionic hydrophilic derivatives of triiodobenzamides of glucosamine (Metrizamide R, Nyegaard), of gluconic acid (P-297, Guerbet), and of our triiodophenyl-beta-O-glucopyranosides have lower toxicity but are hydrolytically unstable. We developed a method for attaching sugars to triiodophenyls as ethers and thus obtained stable derivatives of low toxicity. I.V. LD50s of a bis-glucopyranose triiodophenyl was 17 g I/kgbw. compared to Metrizamide's 12g I/kgbw. We propose further improved nonionic stable CM: a) for uro- and angiography: To synthesize new highly hydrophilic derivatives, based on triiodo-phenyl sugar concept. Our design theory suggests that substituents of triiodobenzene should be not only hydrophilic but also evenly distributed around the ring and attached by nonhydrophobic, stable bonds, preferably allowing for -electron withdrawal. We propose to achieve this by attaching various highly hydrophilic polyhydroxylalkylamines as amides to triiodoisophthalic acid derivatives. b) For subarachnoid space (myelography and computerized tomography (CAT)) we propose to synthesize oliog- and polymers using polyhydroxyl bridges. In oral cholecystography, diagnostic yield of current CM is limited. An improved agent should have high intestinal resorbability as well as biliary excretion (BE). Glucuronate conjugate of iopanoate reportedly increases the maximal rate of BE. We propose synthesis of bis-acylimides of various triiodobenzyl derivatives for rapid resorption from the gut and subsequent liver biotransformation into bis-glucuronides, hopefully to achieve better visualization of the biliary tree as well as low toxicity. All compounds will be characterized and screened by lethal dose determination in protozoan cultures, by I.V. LD50 in mice, by their effect on the lapine isolated heart into cisterna magna in rabbits, and by excretion patterns and effects on other organs which are targets of radiography.